Expression of receptor tyrosine phosphatases during development of the retinotectal projection of the chick

Receptor tyrosine kinases and receptor protein tyrosine phosphatases (RPTPs ) appear to coordinate many aspects of neural development, including axon g rowth and guidance, Here, we focus on the possible roles of RPTPs in the de veloping avian retinotectal system. Using both irl situ hybridization analy sis and immunohistochemistry, we show for the first time that five RPTP gen es-CRYP alpha, CRYP-2, PTP mu, PTP gamma, and PTP alpha-have different but overlapping expression patterns throughout the retina and the tectum, PTP a lpha is restricted to Muller glia cells and radial glia of the tectum, indi cating a possible function in controlling neuronal migration. PTP gamma exp ression is restricted to amacrine neurons. CRYP alpha and CRYP-2 mRNAs in c ontrast are expressed throughout the retinal ganglion cell layer from where axons grow out to their tectal targets. PTP mu is expressed in a subset of these ganglion cells. CRYP alpha, CRYP-2, and PTP mu proteins are also loc alized in growth cones of retinal ganglion cell axons and are present in de fined laminae of the tectum, Thus, the spatial and temporal expression of t hree distinct RPTP subtypes-CRYP alpha, CRYP-2, and PTP mu-are consistent w ith the possibilty of their involvement in axon growth and guidance of the retinotectal projection. (C) 1999 John Wiley & Sons, Inc.